Mechanical dispensers for viscous or extrudable materials include common, piston-type caulking guns found in any hardware store as well as small, hand-held devices for rolling up a flexible tube, such as the tubes that dispense toothpaste. Most extrudable material dispensers employ a piston attached to one end of an elongated piston rod. The piston is advanced through a half or partial-cylinder holder, the shape of which is reminiscent of a trough, the function of which is to hold a cylindrical canister of extrudable material.
Extrudable material in a canister is forced from the canister through a canister tip by driving a canister-internal piston installed into the “bottom” of the canister. The piston in the bottom of the canister is hereafter referred to as a canister piston.
The canister piston drives extrudable material from the canister when the canister piston is driven through the canister by the piston attached to the piston rod. The piston rod is driven by a pistol grip mechanism that forms part of the dispenser. The pistol grip mechanism can be attached to either a ratcheting or ratchetless transmission device. Actuation of the pistol grip causes the piston rod to be advanced into the cylinder, which in turn drives the first piston (attached to the connecting rod) into the second piston (in the bottom of a canister of extrudable material) forcing extrudable material from the dispensing tube. As the first piston moves away from the transmission device and into the dispensing tube, extrudable material is forced from the tip of the canister.
A problem with prior art caulking guns or other dispensers for extrudable materials is that the push rod is relatively long and extends outwardly to make the dispenser unwieldy. The extended rod also makes the device difficult to store or set down between uses, especially when such devices are used in close quarters, as often happens when the devices are used in restaurants to dispense condiments and other extrudable food products. A dispenser for dispensing extrudable material which eliminates the push rod would be an improvement over the prior art.